DosQueryEventSem: Difference between revisions
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DosQueryEventSem returns the post count of the Event semaphore referred to by ''hevSemaphore''. | |||
== Syntax == | |||
rc = DosQueryEventSem( ''hevSemaphore'', | rc = DosQueryEventSem( ''hevSemaphore'', | ||
''pulPostCount'' ); | ''pulPostCount'' ); | ||
=== Parameters === | === Parameters === | ||
;HEV ''hevSemaphore'' (input):The handle (HEV) of the semaphore to be queried. | |||
;PUL ''pulPostCount'' (output):A pointer to the ULONG that is to get the post count of the queried event semaphore. The post count is the number of [[DosPostEventSem]] calls that have been issued for the event semaphore described by ''hevSemaphore''. | |||
The handle (HEV) of the semaphore to be queried. | |||
A pointer to the ULONG that is to get the post count of the queried event semaphore. The post count is the number of [[DosPostEventSem]] calls that have been issued for the event semaphore described by ''hevSemaphore''. | |||
=== Returns === | === Returns === | ||
;APIRET rc:The following values can be returned: | |||
The following values can be returned | |||
{|class="wikitable" | {|class="wikitable" | ||
|0 | |0 | ||
|NO_ERROR | |NO_ERROR | ||
| Line 28: | Line 23: | ||
|ERROR_INVALID_PARAMETER | |ERROR_INVALID_PARAMETER | ||
|Error, One or more parameters is not recognized, See parameters above | |Error, One or more parameters is not recognized, See parameters above | ||
|} | |} | ||
=== Include Info === | === Include Info === | ||
#define INCL_DOSSEMAPHORES | #define INCL_DOSSEMAPHORES | ||
#include <os2.h> | #include <os2.h> | ||
== Gotchas == | |||
The process calling DosQueryEventSem must first obtain access to the semaphore in question or ERROR_INVALID_HANDLE will be returned. | The process calling DosQueryEventSem must first obtain access to the semaphore in question or ERROR_INVALID_HANDLE will be returned. | ||
== Sample Code == | |||
<pre> | <pre> | ||
#define INCL_DOSSEMAPHORES | #define INCL_DOSSEMAPHORES | ||
| Line 61: | Line 54: | ||
</pre> | </pre> | ||
== See Also == | |||
*[[DosCloseEventSem]] | *[[DosCloseEventSem]] | ||
*[[DosCreateEventSem]] | *[[DosCreateEventSem]] | ||
Latest revision as of 07:35, 25 January 2020
DosQueryEventSem returns the post count of the Event semaphore referred to by hevSemaphore.
Syntax
rc = DosQueryEventSem( hevSemaphore,
pulPostCount );
Parameters
- HEV hevSemaphore (input)
- The handle (HEV) of the semaphore to be queried.
- PUL pulPostCount (output)
- A pointer to the ULONG that is to get the post count of the queried event semaphore. The post count is the number of DosPostEventSem calls that have been issued for the event semaphore described by hevSemaphore.
Returns
- APIRET rc
- The following values can be returned:
| 0 | NO_ERROR | Semaphore queried successfully |
| 6 | ERROR_INVALID_HANDLE | Error, The value in phevSemaphore does not point to a valid semaphore, The calling process must first have access to the semaphore in question |
| 87 | ERROR_INVALID_PARAMETER | Error, One or more parameters is not recognized, See parameters above |
Include Info
#define INCL_DOSSEMAPHORES #include <os2.h>
Gotchas
The process calling DosQueryEventSem must first obtain access to the semaphore in question or ERROR_INVALID_HANDLE will be returned.
Sample Code
#define INCL_DOSSEMAPHORES
#include <os2.h>
HEV hevMySemaphore; /* my semaphore handle */
ULONG ulRequestCount; /* will get the request count for the sem */
/* access is gained to the semaphore in question */
/* either by DosCreateEventSem ... */
/* ... or by DosOpenEventSem */
/* its handle is placed in hevMySemaphore */
rc = DosQueryEventSem(hevMySemaphore,
&ulRequestCount);
if (rc != 0)
{
/* We got an error to take care of. */
}